The present invention relates to improved fastenings suitable for personal ornaments such as necklaces, bracelets, belts and the like.
A fastening, which is to be used for linking one end portion to the other end portion of a necklace or bracelet to hold it in the form of an endless belt, should have a relatively small size in consideration of the appearance of the necklace or the bracelet. Usually, use is made of a small fastening having a length of about 6-8 mm and a width of about 3-5 mm.
A hook and eye type fastening is known. Also, a fastening, which has a male screw member and a female screw member, is known. However, the linking operation of such a small fastening behind a neck with the aid of fingers is sometimes troublesome, and required much time.
Furthermore, a modern fastening is also known, which comprises (a) a male member having a projecting portion a (b) a ring-like female member having a relatively large thickness and an opening sufficient to receive the above projecting portion. The internal wall of the ring-like female member is provided with a recess, onto which is partially opened annular spring is placed. When the projecting portion of the male member is forcibly inserted into the opening of the female member, the spring will resiliently engages with the a neck part of the projecting portion of the male member, so that the male member can be adequately engaged with the female member. From the above, it will be seen that the locking and unlocking operations in the modern fastening can be carried out rapidly without any difficulty. However, this fastening has such a drawback that it is difficult to provide the recess by shaving the internal wall of the ring-like female member. Furthermore, it is also difficult to place the partially opened annular spring onto the recess. So, it is unavoidable that the cost for making the modern fastening is considerably high.
It is an object of the invention to provide improved fastenings of the above-mentioned type, which are suitable for personal ornaments. The present fastenings can be manufactured easily and cheaply with high efficiency even on a large commercial scale.
These and other objects, features and advantages of the invention will become apparent from consideration of the following descriptions and the accompanying drawings which are illustrative of a preferred embodiment of the invention.